فهرست مطالب

Journal of Dental Materials and Techniques
Volume:6 Issue: 3, Summer 2017

  • تاریخ انتشار: 1396/04/19
  • تعداد عناوین: 8
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  • Alireza Boruziniat, Nasrin Danaifard, Mahshid Gifani, Narjes Hakimi Pages 96-102
    Aim: To evaluate the effect of storage media and autoclaving on shear bond strength of composite to enamel.
    Materials And Methods
    100 human premolars were randomly divided into ten groups of ten as follows: C: freshly extracted teeth. A: Autoclaved freshly extracted teeth. CH-6: 6 month storage in 0.5 % chloramine T. CA-6: 6 month storage in 0.5 % chloramine T autoclaving. T-6: 6 month storage in 0.04 % thymol. TA-6: 6 month storage in 0.4% thymol autoclaving. Ch-12:12 month storage in 0.5 % chloramine T. CA-12: 12 month storage in 0.5 % chloramine T autoclaving. T-12: 12 month storage in 0.4% thymol. TA-12:12 month storage in 0.4% thymol autoclaving. One composite cylinder was bonded on each specimen for evaluation of shear bond strength (SBS) and failure modes. Data were analyzed using three-way ANOVA, Tukey’s post hoc and Chi square tests and the level of significance was set at P= 0.05.
    Results
    Autoclaving and storage media had no significant effect on SBS (P-value = 0.818 for storage media and P-value = 0.221 for autoclaving). However, storage duration significantly changed SBS (P-value = 0.00). There were no correlations among the variables (P-value > 0.05). Storage media and duration had no significant effect on failure modes (P-value > 0.05), but autoclaving significantly increased cohesive failure of enamel (P-value =0.039).
    Conclusion
    Storage of teeth in chloramine T and thymol had no significant effect on bond strength to enamel. Although autoclaving of specimens may not alter bond strength, it can significantly increase the cohesive failure of enamel.
    Keywords: Autoclaving, bond strength, chloramine T, Extracted teeth, storage media, thymol
  • Poonam R. Kulkarni, Rahul S. Kulkarni, Sumeet Jain Pages 103-107
    Introduction
    The purpose of beading & boxing of an impression is to obtain an accurate cast with proper border & base thickness for fabrication of restorations. Beading is the protection of the formed border thickness of the final impressions & Boxing of an impression is building up vertical walls around it.
    Aim: The purpose of this hybrid technique of beading and boxing is to produce a smooth & aesthetically acceptable cast with accurate border thickness using a simple procedure.
    Materials and Methods
    In this hybrid technique of beading and boxing an impression, a uniform layer of modeling wax was applied over the beading of a plaster-pumice mixture around an impression; after that, boxing & pouring of an impression was done to retrieve a cast.
    Results
    Casts obtained by hybrid technique was more accurate in border thickness & more aesthetic in comparison to the cast obtained by wax technique of beading & boxing.
    Conclusion
    Beading and boxing of an impression is done to protect the formed border thickness of an impression, regulate the height & size of the cast, avoid undue trimming of the cast and to eliminate distortion associated with slumping of the gypsum material when an impression is inverted. This hybrid technique of beading and boxing eliminates the need for applying separating media over the beading of a plaster-pumice mixture and by this technique retrieval of the cast from the impression is very easy and quick. The resulted cast will be very neat and clean with accurate thickness of the borders and base of the cast .This technique is suitable for impressions made from almost any type of impression material.
    Keywords: Mandibular Impression, Dental plaster, Pumice powder, Modeling wax, Final accurate cast
  • Mohammad Javad Moghaddas, Hamideh Sadat Mohammadipour, Roya Amiri Daluyi, Azin Jahan Nia Pages 108-116
    Introduction
    To achieve acceptable clinical performance, a ceramic veneer must be bonded to enamel by well-polymerized resin cement. Among different factors, thickness and translucency of the ceramic may affect the resin cement polymerization. Thus, the current study evaluated the effect of the thickness and translucency of lithium disilicate ceramic on light-cured resin cement bond strength to enamel.
    Methods
    In this laboratory study, 208 sound bovine incisors were equally divided into 16 groups (n = 13). The lithium disilicate ceramic cubes in four thicknesses (0.4, 0.6, 0.8 and 1 mm) with four translucencies (high and medium opaque, high and low translucent) were fabricated and bonded to prepared enamel surfaces using a light-cured translucent resin cement according to manufacturer recommendations. After 5000 cycles of thermocycling, the bonded specimens were placed in a universal testing machine and loaded to the point of fracture. To determine the mode of failure, each sample was observed under a stereomicroscope. Data were recorded and analyzed by Shapiro-Wilk test and two-way analysis of variance (ANOVA).
    Results
    The ceramic thickness and translucency could not significantly affect shear bond strength (SBS) of resin cement to enamel (p = 0.17 and p = 0.097, respectively). The Adhesive and ceramic cohesive failures were reported as the maximum and minimum mode of failure, respectively.
    Conclusion
    The SBS of the light-cured resin cement bonding to enamel and lithium disilicate ceramic was not affected by the translucency of ceramics having a thickness of less than 1 mm.
    Keywords: Dental veneer, IPS-emax press, resin cement, Shear strength, Translucency
  • Payvand Moeiny, Sahar Sayahpour, Farhad Raofie, Alireza Aminikhah, Mohammad Javad Kharazifard Pages 117-124
    Introduction
    Nowadays, thanks to improvements in fruit yoghurt tastes, more tendencies are seen in their consumption especially among children. Therefore, their cariogenicity evaluation as healthy snacks is important. The goal of this study was the assessment of the consumption effect of two kinds of Iranian fruit (apple) and plain yoghurts on dental plaque PH.
    Methods
    In this experimental study, 10 healthy dentistry students were selected upon inclusion criteria. Plaque pH in the certain areas of the mouth was measured by microelectrode and digital pH meter. PH was measured at the baseline and intervals of 2, 5, 7, 10, 15, 20, 30, 40, 50 and 60 minutes after eating test products: fruit yoghurt (apple) and plain Yoghurt. For positive control group, just the baseline PH and at intervals of 2 and 5 min after swishing with 10% sucrose solutions were recorded. The results were analyzed using repeated measures ANOVA.
    Results
    Lowest pH was obtained after fruit yoghurt consumption followed by plain yoghurt and %10 sucrose solution and the plaque PH difference was significant (P=0.05). Furthermore, time duration which remained below the critical pH was longer after consuming fruit yoghurt.
    Conclusion
    Both kinds of yoghurts were considered cariogenic since plaque pH drop below critical points. Average of plaque pH after consuming fruit yoghurt was significantly lower in almost all the time intervals.
    Keywords: Acidogenicity, Plaque PH, Plain yoghurt, Fruit yoghurt, cariogenicity
  • Alireza Boruziniat, Mostafa Babazadeh, Mahshid Gifani, Monavar Nasirzadeh Pages 125-130
    Aim: To determine the effect of different concentrations and application times of tannic acid on bond strength to dentin.
    Materials And Methods
    Occlusal surfaces of 180 human molars were randomly divided into two groups of immediate shear bond strength evaluation and evaluation after 2 months of storage in collagenase solution. Each group was divided into 10 subgroups according to the solutions applied: no additional treatment (control), chlorhexidine 2% (Positive control), tannic acid 20% (30s, 1 min, 3min, 5min) and Tannic acid 30% (30s, 1 min, 3 min, 5 min). Failure mode were assessed using a stereo-microscope. The data were statistically analyzed by One-way ANONA and Tukey’s post hoc test.
    Results
    There was no significant difference in immediate bond strength among experimental groups. However, after 2 months storage in collagenase solution, a significant difference was found among the groups. Bond strengths of CHX and 20% TA applied for 3 minute were significantly higher than the control group.
    Conclusion
    Use of tannic acid and chlorhexidine has no negative effect on immediate shear bond strength. However, their application significantly prevents compromised bond strength caused by storage in collagenase solution.
    Keywords: Bond durability, tannic acid, Chlorhexidine, matrix metalloproteinases
  • Hamidreza Arabion, Mahdi Gholami, Habibollah Dehghan, Hussein Khalife Pages 131-137
    Objectives
    The prevalence of impacted teeth fluctuates across various ethnicities and geographical regions. The aim of the present study was to evaluate the prevalence and patterns of impacted teeth among patients living in the central part of Iran.
    Methods
    This retrospective study was conducted on 3632 patients within the age group of 17-30 years. The frequency and pattern of the impaction were determined using orthopantomogram (OPG).
    Results
    According to the results of the study, 56.3% of the patients were female (n=2046). Out of the 3632 OPGs, 1602 cases (44.1%) were detected with at least one impacted tooth. No significant difference was observed between the males (n=682; 42.6%) and females (n=920; 57.4%) in this regard (P=0.237). Furthermore, the third molars were the most common impacted teeth found in 1156 radiographs (31.8%) with no significant difference between the males (n=358; 30%) and females (n=798; 70%) (P=0.386). Mesioangular and distoangular impactions were detected to be the most frequent angulation of the impacted third molars in the mandible (49%) and maxilla (41%), respectively. Additionally, 357 (9.8%) and 78 (2.1%) cases showed at least one impacted maxillary canine and one impacted mandibular second premolar, respectively. Moreover, impacted ectopic teeth were observed in 11 (0.3%) individuals.
    Conclusion
    Based on the findings of the present study, the third molar was the most common impacted tooth observed in the people living in the central region of Iran, followed by canine and second premolar impaction. The prevalence of the third molar impaction in the females was nearly twice as much as that in the males.
    Keywords: Impacted teeth, Orthopantomogram, Young Adults
  • Javad Sarabadani, Sahar Heydari, Amirreza Mashreghi, Niloofar Poornazari Pages 138-141
    Focal epithelial hyperplasia or Heck’s disease is a rare benign lesion of oral mucosa caused by human papilloma virus especially subtypes 13 and 32. The disease is predominantly found in children and adolescents with indigenous heritage. This paper reports a unique case of Heck's disease in an 11-year-old Iranian girl with multiple, bilateral and elevated lesions on the buccal and labial mucosa. The lesions had persisted for a year. The disease was diagnosed as focal epithelial hyperplasia through the clinical examination. Considering esthetic and functional problems, CO2 laser (Wavelength: 10600 nm) surgery was determined as a suitable choice of treatment. The patient was followed up over 1 year with no signs of lesion recurrence.
    Keywords: Focal Epithelial Hyperplasia, Heck's Disease, CO2 laser, Carbon Dioxide Laser, Case report
  • Elham Najafi, Hamid Jafarzadeh, Mahsa Dastpak Pages 142-146
    Tooth autotransplantation defines as transition of one tooth from one position to another, in same individual. It is a biological procedure in which teeth have the potential to induce alveolar bone growth. It can be applied in patients before adolescence growth is finished. It significantly reduces time and cost compared to implants. Healing rapidly occurs and function is regained almost immediately. Our case was a 15-year-old male that his left mandibular third molar transplanted to the second molar sight after extraction of second molar because of unrestorable crown. During 9 month follow up transplanted tooth was asymptomatic, functional and responsive to sensibility tests. (Cold test, EPT).
    Keywords: Autotransplantation, mandibular molar, unrestorable crown, Case report